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UNITED STATES-PATENT; orFroE.

HARRY B. eoonwm, or GRAND JUNCTION," coLonAno, ssmnon 'ro THE LATIMEBXCHEMICAL COMPANY, a com'omnon'or cupp ng (pr ARSENATE or LEAD;

To all whom it may concern:

Be it known that I, HARRY B. Goonwm,

a citizen of the United States, residing at Grand Junction, State ofColorado, have invented certain new and useful Improve ments in Arsenateof Lead, of which the following is a specification.

Arsenate of lead is used generally forthe killing or elimination ofvarious insect enemies to various forms of vegetation and finds a largeuse to this end in orchards. It

' has now become a. common practice to spray arsenateof lead onto fruittrees which, without some treatment,,,may be, subject to an injuriousattack by various insects. The insects commonly attack both the leaf andI the fruit. They are sometimes very small,

being almost invisible to the naked eye, and .it is nearly impossible tolocate them on the trees. It becomes necessary therefore, to

' cover both'the trees and their foliage with some material poisonous tothe insects. Arsenate of lead is generally admitted to be very eificientfor this end and it is common-ly used'by orchard owners and recomArsenate of lead is ofiered. commercially in two forms, paste .andpowder. While the paste form has been found eflicientas an insecticide,it is diiiicult to produce a productflin' the paste form that will stayuniform until it is used. Arsenate of lead in the powdered form is,therefore, being more generally used.

18 pound of arsenate of'lead-powder-is' gen- When used for. sprayingfruit trees 1 erally. added to .50 gallons of water.-'.The

arsenate of leaddoes not dissolve in the. water but is-held insuspension in it" and the physical mixture of water and arsenate ofleadisthen p he -water evaporates leaving-- the 'arse'nate 'oflead'adhering tothe'trees where iti' nay i be found and poison may be readilyavailabletd'the'in tributed on the trees it is necessary have it more.or less uniformly suspended in the lead vPb C 0 -'-'and arsenic a cidH,A sQ;-v which, by the process I emplo'y,produces a assed through spraing tip-, I aratu and so distributed on t e.. tree s..-

consumed. by the-insects Ito be;destroyed. In] order to get satisfactoryresults from thearsenate of lead treatment it is necessary to have thepoisonthoroughly;- distributed over the trees. sogj ljlthat {the waterin the spraying tank-and in the water as it is delivered by the spray.tothe trees. It is the desire of the manufacturer of arsenate of lead,therefore, to produce a product which may readily be suspendedin.

Patented-Nov.18,1919. i918. Seria1 No.248,343i

water and which' when mixed with water,

will remain in' suspension; To this end .much efiort has been devoted toproducing arsenate o f leadin a'fine impalpable powder.-

To a limited degreethese eflorts havebeen successful and there are onthe market ow dered arsenates of lead which may be a ded to water andbyagitation thoroughly mixed and gotten in suspension. Prior to myinvention-there has been no varsenate of leadwhich would remain insuspension for long under commercial conditions or in the proportionsusually employed for spraying.

his the 'obyect of .mysinvention to provide an arsenate of leadcomposition which will not only readilybecome suspended in water but.will remain suspended in the .Water for, a considerable period-of time Iunder ordinary conditions'and when added to water in the.proportionsgefierally adopted for spraying.

.While not necessarlly confined to such'material I.- refertto-employ anarsenate of r need bymixing lead acetate very fine precipitateofarsenate ofjlead. I find thatarsenate of lead so produced may a 15grains of dry material to 250 cubic centimeters-"of'water and afterproperly agitat- .ing to get all the "material in suspenslon in thewater, to let rest quiet and then measure the: amount "of clear water atthe top of the column at the end of five minutes, and-again at the endof ten This is a conven 'entand 'easyi test but it .does not simu- 1late practioal'condi-tions for the reason that the ratio of 15- grams to250 cublc centimeters of water is equivalent 01 25 pounds to 50 agallons, The usual orchard strength'of arse .nate of'le'ad mixture isonly ,1

ned-of pow:

der to fio gallons of water.- oreover,

clearwater proportion in the top of the scale is not of as muchimportance as the general distribution of material throughout the bodydistributed throughout the liquid.

In order, therefore, to determine the condition existing undercircumstances such as are met in practical use of arsenate of lead asaninsecticide, I have made a test by mixing a sample of arsenate of leadin the proportion of 1 pound of the powder arsenate of lead to 50gallons of water. After thor- .oughly mixing, agitating, and gettingsub-- stantially all of the arsenate of lead in suspension in the water,it was allowed to re-.

main quiet for five minutes at the end of which time the upper half ofthe liquid and the arsenate of leadsuspended therein was siphoned 0dfrom the top of the vessel into a weighed dish. The liquid so siphonedofi was then evaporated to dryness and the residue weighed. One half theweight of the entire quantity of arsenate of lead suspended originallywas then divided into the weight of the dried residue remaining in thedish. This gives the'per cent.-of arsenate of lead remaining insuspension in the upper half of the liquid. By repeating the test andletting the mixture rest quiet for longer periods it is possible .toobtain information of practical value concerning the continuance ofsuspensibility of the arsenate'of lead in water.

, In the particular sample tested 1 find that there still remained insuspension in the upper half-of the fluid at the end of 5' minutes31.91% of the arsenate of lead. At the end of 10 minutes there remainedsuspended in the upper half only 10.04%. At the end of 20 minutes thereremained suspended 8.25%. At the end of.40 minutes 6.16%. At'the end of80 minutes 1.87%. .The same material when tested by the ordinary methodof adding 15 grams to 250 cubic centimeters of water showed at theend of5' minutes only 2 cubic centimeters'of clear water and at the end of 10minutes only 4 cubic centlmeters' of clear water which figures 1nd1catethat, according to the ordinary method of testing, it is a product ofvery hlgh qual1tyand indeed it is the best product T can find on themarket.

- I find that if I add to the arsenate of lead used in the above test aquantity of commercial tannin I obtain a much superior suspensibility.The tannin which I have used is the brown powder of commerce producedfrom the bark of chestnut trees, commerclally known as Chestnut B butthis speclfic kind of tannin is not essential to my invention. The exactproportion of tannin the tannin.

to arsenate of lead is not material, although I have found of 1% oftannin satisfactory but the quantity may be varied within wide limitsas-T have gotten good results with less than of 1% and again with asmuch as 10% or more. I find however, thatamixture of of 1% of tannin issuflicient for practical purposes and has no ill efi'ect on theinsecticidal properties of the arsenate of lead. On adding this mixtureof arsenate .oflead and J; of 1% of tannin to water in the orchardproportions of 1 pound to 50 gallons I find that after shakingthoroughly and mixing them and then leaving still for 5 minutes andsiphoning oil the upper half of the liquid and its contents as in thelast test, there remained suspended 88.93% as against 31.91% when tanninwas not used. At the end of 10 minutes there was suspended 84.45%v asagainst 10.04%, when tannin was not used. At the end of 20 minutes81.08%. At the end of 40- minutes 74.75%. At the end of 80 minutes62.67%. At the end of 140 minutes 47.70%. At the end of 200 minutes41.75% as against 1.13% at the end of 200 minutes when no tannin wasused.

The value of the comparative settling tests as outlined above is thatthey offer simple means of determining the physical qualities or fitnessof the material.

The active principle of tannin is tannio acid and the tannin mentionedabove contains about 60% of tannic acid. In another and in this wayobtained substantially the same result as when 4 of 1% of tannin wasused.

tion of fineness I believe that the added tannin causes the arsenate oflead to become or I remainin a very finely divided state which alsocauses it to have an increased covering capacity on the tree thuseffecting a marked economy in the quantity needed for an orchard but Iam not sure of this theory and my invention does not depend thereon.

In order to achieve benefits by the use of my invention it is notnecessary that the arsenate of lead to which the tannin is added bechemically pure as various impurities may be present in small or minutequantities without materially diminishing the effect of I find however,that if there be present in the arsenate .of' lead a small quantity oflitharge or of acetate of lead the increased suspensibility otherwiseproduced by tannin is not obtained. Minute quantities of lithargepresent do not affect the result. For instance, in a sample of arsenateof lead in which there was present one tenth of 1% of lithargesubstantially as good results 105 Since suspensibility generally is'afunci of tannin as if the litharge had not been present. With a sampleof arsenate of lead in which there was present one tenth of 1% of leadacetate substantially as good results were obtained by the addition ofof 1% of tannin as if the acetate of lead had not been present. However,a sample of arsenate of lead containing approximately 1% of litharge wassubstantially unafi'ected as to its capacity for remaining suspended inwater by the addition of s of 1% of tannin. Likewise a sample containingapproximately 1 of lead actate was similarly unaffected by the additionof gof 1% of tannin. Some of the commercial methods of manufacturingarsenate of lead leave an excess of free litharge or free lead acetatein the finished product. If the arsenate of lead made by these methodsis not properly purified it is put upon the market containing some ofthese salts. I find, therefore, th at some of the arsenates of lead onthe market do not lend' themselves, because of the impurities contained,to the production of the beneficial results to be obtained by theaddition of tannin to purer arsenate of lead.

My invention is not confined in its application to powder arsenate oflead nor to that made by the process set out above for, by whateverprocess it is made, if it is properly and sufficiently purified, it willlend itself to my discovery and more especially so if it is reduced tofine soft particles 'before'tannin is added. v 1

I find it convenient to add the dry powdered tannin or tannic acid tothe prepared powdered arsenate of lead but it may be that equally goodresults can be obtained by adding the tannin or tannic acid to thearsenate of lead at some intermediate stage in the to its mixture withthe water.

process of manufacture or even subsequent Numerous from the details setout above may be resorted to without departingfrom my invention.

I claim as my invention:

1. A mixture of arsenate of lead containing less than one'per cent. offree litharge, and tannin.

2. A mixture of arsenate of lead containing less than one per cent. offree lead ace. tate, and tannin. g

3. A mixture of arsenate of lead, and one half of one per cent. oftannin by weight.

4. A mixture of arsenate of lead, and sufficient tannin to increase thepersistence of suspensibility of the arsenate of lead in water.

5. The method of increasing the persistence of suspensibility ofarsenate of lead c in water consisting in adding one half of one percent. of tannin to powdered arsenate o ead.

6. The method of increasing the persistence of suspensibility in waterof arsenate of lead, consisting in mixing tannin there within the drypowdered form.

7. A mixture of tannin and the precipitate formed by mixing lead acetateand ar-' senic acid.

8. An insecticide of which the principal active ingredient is arsenateof lead with less than 1% of free lead acetate and less three tenths of1% of tannic acid.

9. A mixture of dry, soft, bulky, powdered arsenate of lead,-andapproximately one half of one per cent. of tannin by weight.

H] B. GOODWIN.

7s. than 1% of free litharge and more than

